pingx.c

/*
 ============================================================================
 Name        : pingx.c
 Author      : Ray Cheung
 Version     :
 Description : ping multiple host
 ============================================================================
 */
#include <ctype.h>
#include <stdio.h>
#include <stdlib.h>
#include <stdbool.h>
#include <string.h>
#include <unistd.h>
#include <netdb.h>
#include <arpa/inet.h>
#include <time.h>
#include <sys/time.h>
#include <sys/socket.h>
#include <sys/select.h>
#include <netinet/in.h>
#include <netinet/ip_icmp.h>

#define ICMP_PACKET_LEN 64
#define ICMP_DATA_LEN   56
#define ICMP_SEQ_START  4000

typedef struct {
	char *hostname;
	int rtt;
} alive;

extern unsigned short chksum(unsigned short *addr, int len);
extern void pack(int seq, char *packet);
extern bool unpack(char *buf, int len, struct timeval tvrecv, alive *alives);
extern struct sockaddr_in getaddrbyhostname(char* hostname);
static void tv_sub(struct timeval *out, struct timeval *in);
extern void ping(alive *alives, int count, struct timeval timeout, int try_times);
static void usage_with_exit();

unsigned short chksum(unsigned short *addr, int len) {
	int nleft = len;
	int sum = 0;
	unsigned short *w = addr;
	unsigned short answer = 0;

	/*把ICMP报头二进制数据以2字节为单位累加起来*/
	while (nleft > 1) {
		sum += *w++;
		nleft -= 2;
	}
	/*若ICMP报头为奇数个字节，会剩下最后一字节。把最后一个字节视为一个2字节数据的高字节，
	 这个2字节数据的低字节为0，继续累加*/
	if (nleft == 1) {
		*(unsigned char *) (&answer) = *(unsigned char *) w;
		sum += answer;
	}
	sum = (sum >> 16) + (sum & 0xffff);
	sum += (sum >> 16);
	answer = ~sum;
	return answer;
}

void pack(int seq, char *packet) {
	int packsize;
	struct icmp *icmp;
	struct timeval *tval;
	icmp = (struct icmp*) packet;
	icmp->icmp_type = ICMP_ECHO;
	icmp->icmp_code = 0;
	icmp->icmp_cksum = 0;
	icmp->icmp_seq = seq;
	icmp->icmp_id = getpid();
	packsize = 8 + ICMP_DATA_LEN; //icmp_type 1, icmp_code1, cksum 2, seq 2, id, 2 共8字节
	tval = (struct timeval *) icmp->icmp_data;
	gettimeofday(tval, NULL);
	icmp->icmp_cksum = chksum((unsigned short *) icmp, packsize);
}

bool unpack(char *buf, int len, struct timeval tvrecv, alive *alives) {
	int iphdrlen;
	struct ip *ip;
	struct icmp *icmp;
	struct timeval *tvsend;
	double rtt;
	ip = (struct ip *) buf;
	iphdrlen = ip->ip_hl << 2; /*求ip报头长度,即ip报头的长度标志乘4*/
	icmp = (struct icmp *) (buf + iphdrlen); /*越过ip报头,指向ICMP报头*/
	len -= iphdrlen; /*ICMP报头及ICMP数据报的总长度*/
	if (len < 8) /*小于ICMP报头长度则不合理*/
	{
		return false;
	}
	/*确保所接收的是我所发的的ICMP的回应*/
	if ((icmp->icmp_type == ICMP_ECHOREPLY) && (icmp->icmp_id == getpid())) {
		tvsend = (struct timeval *) icmp->icmp_data;
		tv_sub(&tvrecv, tvsend);
		rtt = tvrecv.tv_sec * 1000 + tvrecv.tv_usec / 1000; /*以毫秒为单位计算rtt*/
		int seq = icmp->icmp_seq;
		if (alives[seq - ICMP_SEQ_START].rtt >= 0) {
			return false;
		}
		alives[seq - ICMP_SEQ_START].rtt = rtt;

		return true;
	}
	return false;
}

void tv_sub(struct timeval *out, struct timeval *in) {
	if ((out->tv_usec -= in->tv_usec) < 0) {
		--out->tv_sec;
		out->tv_usec += 1000000;
	}
	out->tv_sec -= in->tv_sec;
}

struct sockaddr_in getaddrbyhostname(char* hostname) {
	struct sockaddr_in addr;
	bzero(&addr, sizeof(addr));
	struct hostent *host;
	addr.sin_family = AF_INET;
	if ((host = gethostbyname(hostname)) == NULL) {
		addr.sin_addr.s_addr = 0;
	}else{
		addr.sin_addr = *((struct in_addr *) host->h_addr);
	}
	return addr;
}

void ping(alive *alives, int count, struct timeval timeout, int try_times) {
	struct protoent *proto = getprotobyname("icmp");
	int sockfd = socket(AF_INET, SOCK_RAW, proto->p_proto);
	int i;
	for (i = 0; i < count; i++) {
		struct sockaddr_in dest_addr = getaddrbyhostname(alives[i].hostname);
		if (dest_addr.sin_addr.s_addr == 0) continue;
		char buf[ICMP_PACKET_LEN];
		pack(ICMP_SEQ_START + i, buf);
		int times = try_times;
		while(times > 0){
			if (sendto(sockfd, buf, ICMP_PACKET_LEN, 0,
					(struct sockaddr *) &dest_addr, sizeof(dest_addr)) < 0) {
				fprintf(stderr, "send error %s.\n", alives[i].hostname);
			}
			times--;
		}

	}
	time_t loop_start = time(NULL);

	fd_set fdset;
	FD_ZERO(&fdset);
	FD_SET(sockfd, &fdset);
	int matched = count;
	while (matched > 0) {
		if (select(sockfd + 1, &fdset, NULL, NULL, &timeout) == 0) {
			break;
		}
		if (!FD_ISSET(sockfd, &fdset)) {
			continue;
		}
		time_t current = time(NULL);
		if (current - loop_start > timeout.tv_sec * 1000) {
			break;
		}
		char buf[ICMP_PACKET_LEN];
		struct sockaddr_in from;
		size_t from_size = sizeof(from);
		int buflen = recvfrom(sockfd, buf, ICMP_PACKET_LEN, 0,
				(struct sockaddr *) &from, &from_size);
		if (buflen < 0) {
			continue;
		}
		struct timeval tvrecv;
		gettimeofday(&tvrecv, NULL); /*记录接收时间*/
		if (unpack(buf, buflen, tvrecv, alives)) {
			matched--;
		}
	}

}

void usage_with_exit() {
    printf("Usage: pingx [-c count] [-t timeout] IP1 [IP2 [IP3]]\n");
	exit(EXIT_FAILURE);
}

int main(int argc, char **argv) {
	int arg_timeout = 3;
	int arg_count = 3;
	int c;
    while ((c = getopt(argc, argv, "ht:c:")) != -1)
		switch (c) {
		case 't':
			arg_timeout = atoi(optarg);
			break;
		case 'c':
			arg_count = atoi(optarg);
			break;
		case 'h':
            usage_with_exit();
			break;
		case '?':
			if (optopt == 'c' || optopt == 't')
				fprintf(stderr, "Option -%c requires an argument.\n", optopt);
			else if (isprint(optopt))
				fprintf(stderr, "Unknown option `-%c'.\n", optopt);
			else
				fprintf(stderr, "Unknown option character `\\x%x'.\n", optopt);
			return 1;
		default:
			usage_with_exit();
		}
    if (arg_timeout <= 0 || arg_count <= 0) {
    	usage_with_exit();
    }
	int host_count = argc - optind;
	if (host_count == 0) {
		usage_with_exit();
	}

	if (geteuid() != 0) {
		fprintf(stderr, "Permission Denied\n");
		exit(EXIT_FAILURE);
	}
	char** hostnames = &argv[optind];
	alive alives[host_count];
	int i;
	for (i = 0; i < host_count; i++) {
		alives[i].hostname = hostnames[i];
		alives[i].rtt = -1;
	}
	struct timeval tv;
	tv.tv_sec = arg_timeout;
	tv.tv_usec = 0;
	ping(alives, host_count, tv, arg_count);
    bool has_unreachable = false;
	for (i = 0; i < host_count; i++) {
		printf("%-20s\t%d\n", alives[i].hostname, alives[i].rtt);
        if (alives[i].rtt < 0) {
            has_unreachable = true;
        }
	}
    if (has_unreachable) {
        return EXIT_FAILURE;
    }else{
        return EXIT_SUCCESS;
    }
}